Spark-plug.



C. P, JOHNSTON.

SPARK PLUG. APLIOATION FILED PEB. 4, 1911.

mami@ Patented May 13, 1913.

f5.5 pnsionfrom cracking the insulating mem- UNrTEDj STATES' PATENT OFFICE.

CHARLES F. JOHNSTON, or MARSHA'LLTOWN, IOWA, AssIGNoR or ONILHALF To CHARLES c. ELDRIDGE AND oNnHALF '.ronnwIN J. BEEBE, Borriv or man SHALLTOWN, IOWA.

Specifica-.tion of Letters Patent.

sym-PLUG.

Patented May 13, 1913.

Application filed February 4, 1911.- Serial No. 606,477.

One of the objects `of' this invention to- 1o produce an improved spark plug by means ofwhich a considerably larger spark may be Y obtained than has heretofore been posslble. f -Another lobject is to produce a spark plug vwhich will'need cleaning less frequentlyi lsthan prior plugs, and Whichmay bei-more 'easily cleaned when cleansing lbecomesnec, essay. V y

In he accompanying drawings, Figure l is a side elevation of a spark plug embodying the features of In' invention. Fig. 1s

a bottom plan view o the plu ig. 3 isa. longitudinal central sectional view. F1gs,-` 4|, 5, and 6` illustrates three forms of clips' by 'means of which electrical conductors may 125 bei-attached to the plug.

" Th'e present embodiment of my invention. comprises a casing 1 in the form of a' bu shingadapted to be screwed into an engine cylinder, said 4casing `having a member 2 J0 therein which is formed of insulatingmaterial '-such as porcelain. The insulating member 2 may be held in place in the casingl` in any suitable-way as by an annular i flange 3 on said member engaging an annu- .35 lar shoulder within the casing, and a nut 4 .threaded in the' casing and en aging the opposite side of said flange. ne of' the `electrodes may be in the form of a rod 5 extending through a central opening 6 in 4U the insulator 2, said rodprojecting from the ends of said member, and being threaded at its upper end to receive a nut 7, to hold the-electrode in place, and-a cap to be later described. A coating of adhesive cement 8 surrounds the rod 5 withinlthe opening 6. -The lower end of the opening may be enlarged as shown, and withmthis enlargementis placed a packing 9 of asbestos o r the like, said packing surrounding the rod and being held in place-by a shoulder l0 on said rod.4

In use, the end of the electrode which lies within the engine cylinder becomes hotand expands. The packing 9 prevents such ex- The electrodes 11 of opposite polarity to the electrode' may besecured in the lower end of the'casing 1, said electrodes 11 being herein shown in the form of short wires arranged symmetrically around the central electrode 5 and extending inwardly to lie at a suitable distance from the electrode 5. The outer end portions 11* lof the 'electrodes 11 are bent to lie parallel with the central electrode, so that instead of a spark being '.formed aten-ly the-points of each ofthe electrodes 11,' a large spark is formed along 4`the. entire end portion'll. It will be seen that when a current passes throughA the spark plug, it willj ump the gaps from `the electrode 5 to the long end'portlons of each of the electrodes .ll of opposite polarity, thereby producing a much larger spark than has heretofore. been obtainable.

Upon the upper end of the electrode 5 is threaded a cap 12 having two annular iangesv 13 :near its lower end. T he upper end of the cap 12 has an opening 14 therein yof a size'adaptedto tit upon the lower end of the central electrode 5. Said upper end may be reduced as at l5 to .a suitable size.

In case the electrodes 11 get burned off or bentout of position slightly in cleaning, the

-opening 14 in the cap- 12 may be slipped upon the lower end of the electrode 5, as shown in dotted lines in Fig. l, and the electrodes 1 1 bent inwardly against the reduced end 15 of said cap. The cap12 thus forms a convenient and ready means for spacin the electrodes 11 at the proper distance rom the central electrode 5.

- It' wi'll'be Observed that, in the plug herein shown, the electrodes project outwardly a considerable dist-ance from the casing and the spark is made at the outer end portion of the electrodes. In spark plugs .in which the electrodes are inclosed or partially inclosed in the housing;around the electrodes, the

lhousing reventing ood access of the fresh charge o gas to the e ectrodes, and imperfect ignition is the result. This imperfect ignition causes a rapid deposit of carbon upon the electrodes. which necessitates theiufrequent cleaning.

In my spark plug, the electrodes project-fi relatively great distance beyond the casing of the plug and the parallel portions 11 where the spark is formed are 'at'the' itrexne ends of the electrodes. A large spark` is therefore drawn at a pointfwell away from the wall of the enginecylinder where there is not-hing to hinder the incoming fresh broken up` into a multitude of eddy currents which w1ll sweep. around and among the" electrodesA in various direct-ions and thus tend to remove any deposit of carbon there'- from. Inasmuch as a large spark is drawn at ya point freely`,-accessible tothe incoming.

charge of 'fresh gases, the very besti nitionis obtained. VVhen'the ignition is Goo the de-l posit 'of carbo-n on the electro' es is corre` spondingl small, and the electrodes do not require ceaning so frequently. The four outer electrodes form a screen to prevent carbon from bridging the space between said central electrode and any of said outer elec'- trodes. If one or even three of the electrodes should become coated with soot so as to render them unserviceable, a spark would still be drawn at the remaining electrode. The period between the times-lat which the plug demands cleaning is thus further prolonged.. However when it becomes necessaryto' clean the electrodes, they are readily accessible and easily .cleaned If they become deranged in'f'cleaning they may be again properly ositioned by means of the 4cap 12, as herein efore explained, or in any V other suitable way.

In' Fig. 4, I have shown an electric-wireattaching member consisting of a flat strip having an' eye 16 therein adapted to fit over 'the upper end ofthe electrode 5, and be held in place by the cap l2, said member comprising a portion 17 around which a wire may be bent and soldered if desired.

In Fig. 5 is shown a clip having an opening 18 therethrough and a slot 1S) extending through said opening to provide two arms 20. This clip may-be sprung around the cap'l2 between the flanges 13, the cap lying within the opening 18. A portion 21 is adapted to have an electric wire bent therearound for supplying current to the spark lug.

VFig'G illustrates another form of'clip 22 comprising a ball 23 having an opening 24 therethrough, and a' slot 25 forming spring arms 26, said ball being adapted to be slipped over the upper end of the cap 1.2. An electric wire may be attached to the op posite end of the clip.

It will be understood that none of the clips shown in Figs. 4, 5 and 6 is necessary. If desired, a Wire may be wound about the upper end of the electrode 5, and the cap .turned down upon the wire to make a good `prising a casinor .an engine cylini Contact and hold the wire in place. The forms of clips illustratedin Figs. 4, f and 6 are at presentu on the market.

It will be seen i iat I have provided a plug which is adapted 'to have an electric wire attached, thereto in any one of several of the methods at present-Tin use. This feature has been found-a'great convenience in practice.

I claim asmy invention.'

l. An improvement in-spark plugs com'- adapted tobe screwed into er, an insulating sleeve supported by said casing, a central electrode extending through said sleeve and projecting from one end thereof, 'and four electrodes of opposite polarity to' said central elect-rode and arranged substantially symmetrically around the latter, the outer electrodes being each fixed at one end to the inner end of the casing, the free ends -of said outer electrodes bein bent to lieapproximately parallel to said central electrode to form a screen to prevent carbon from' bridging the space between said central electrode -and any of said outer electrodes, said pa-ral lel ends creating a large spark and -serving to break up. the incoming charge of fresh gases into eddy currents, whereby the electrodes will be scoured at each cycle of the engine. l A

2. An improvement'in spark plugs comprising a casing adapted to be screwed into an engine cylinder, an insulating sleeve supported by said casing, a central electrode extending through said sleeve and projecting from one end thereof, and four electrodes of opposite polarity to said central electrode and arranged substantially symmetrically around the latter, the outer electrodes being each fixed at one end to the inner end of the casing, the free ends of said outer electrodes being bent to lie approximately parallel to said central electrode to form a screen to prevent carbon from bridging the space between said central electrode and any of saidouter electrodes7 said parallel ends creating a large spark and serving to break up the incoming charge of fresh gases into eddy currents, whereby the Aelectrodes will be scoured at each cycle of the engine, said electrodes being uni'nclosed and all .extending far enough from said casing and said insulating member respectively to -project beyond the zone of dead gases normally within the engine cylinder, whereby prompt ignition is insured. A In testimony whereofl hereto aliX my signature in the presence of two witnesses. CHARLES F. JOHNSTON. Witnesses L. L. MILLER, JosnrI-r R.`BARsE, Jr.

i Copies of this patent may be obtained for ave cents each, by addressing the Commissioner of Patenti,

Washington, D. C." 

